The invention described and claimed in parent application Ser. No. 10/729,920 provides a surface acoustic wave sensor or identification device having a piezoelectric substrate, an interdigitated transducer (IDT) input/output mounted on the substrate for receiving a radio frequency (RF) signal and propagating a corresponding surface acoustic wave along a surface of the substrate, and an IDT reflector array mounted on the substrate and operable to receive the surface acoustic wave and reflect the surface acoustic wave in modified form back to the IDT input/output for transmission of a corresponding modified RF signal from the device. The IDT reflector array has at least one reflector sector whose reflectivity characteristics are controlled to control the nature of the modified RF signal. The device also includes at least one reflector segment having a fluidic chamber which in use contains fluid operable to control the nature of the reflected surface acoustic wave and hence the nature of the modified RF signal.
It is an object of the present invention to provide a surface acoustic wave sensor or identification device of this kind which has a biolayer which is modified by the fluid in the fluidic chamber.